Blasting devices



Jan. 9, 1962 E. c. FILSTRUP 3,

BLASTING DEVICES Filed May 14, 1959 FIG. 1

IN V EN TOR.

EDWARD C. FILSTRUP JR.

BY W 5 States 3,16,15 Patented Jan. 9, 1962 3,016,015 BLASTHJG DEVICESEdward C. Filstrup, St. Joseph, Mich, assignor to Olin MathiesonChemical Corporation, East Alton, 11]., a corporation of Virginia FiledMay 14, 1959, Ser. No. 813,230 7 Claims. (Cl. 102-25) This inventionrelates to blasting devices and more particularly to material breakingcartridges utilizing a gas under pressure as the work performing medium.

Material breaking cartridges using compressed gas to execute therequired work are well known and widely used in the mining industry.Such cartridges or blasting devices are all reliant upon the suddenrelease of compressed gas to give a quasi explosive eifect. Theprecursor of this type of blasting cartridge consisted essentially of acylindrical gas-containing cartridge having venting means. Thecartridges were charged with gas under considerable pressure, sealed andthen conveyed to the face to be worked. The compressed gas within thesecartridges was released by elaborate remote control means. Morerecently, the practice has been to place an uncharged cartridge in thebore hole and pump gas through a suitable conduit into the cartridge insitu. Conventionally, these cartridges are formed of high strengthmaterials and are provided with a relatively weak member which shears orruptures so as to liberate the gas from the cartridge body. Since theamount of pressure that can be built up in the cartridge body isdependent upon the strength of the expendable member, the quantity ofenergy developed by the liberation of the gas can be controlled withinrelatively close limits. Such cartridges have met with general successin the field but are difficult to manufacture and maintain. They areconventionally fired at pressures in the neighborhood of 10,000 psi. andrequire a relatively large number of reliable seals to insure properfunctioning. The manufacture and maintenance of such seals has in thepast proved expensive and exceedingly inconvenient. Thus, thedevelopment of a shell having a minimum number of seals has long beenrecognized as a desirable goal. Furthermore, the current materialbreaking shells are difiicult to disassemble, repair and reassemble. Inmost instances, this must be done at a work bench and not in the area inwhich the shell is being used.

Therefore, it is an object of this invention to provide new and improvedmaterial breaking devices utilizing compressed gas. A further object ofthis invention is to provide a simplified device of this characterhaving a minimum number of seals. Another object of this invention is toprovide a shell having a rupturable release member that can be used anumber of times. Still another object of this invention is to provide acompressed gas material breaking cartridge overcoming the disadvantagesof the prior art.

The manner in which these and other objects are accomplished will beapparent from the following specification together with the drawing inwhich:

FIGURE 1 is a longitudinal sectional view of a device illustrating oneembodiment of the present invention;

FIGURE Z is a longitudinal sectional view of a device illustratinganother embodiment of the present invention;

FIGURE 3 is a perspective view partially in section of the sleevevalv'eemployed in the embodiment shown in FIGURE 2; and

FIGURE 4 is a plan view of the shear plate utilized in the embodiment ofFIGURE 2. p

Referring to FIGURE lwhich illustrates a preferred embodiment of theinvention, an elongated tubular body formed of metal, reinforcedsyntheticplastic material, or

the like, of a strength to contain gasunder high pressures,

for example pressures from 6,000 to 20,000 pounds per square inch, isindicated generally at 1. Only a portion of this tubular body which maybe of the order of 50 inches in length is shown. The outer diameter ofthe body is such that it may be set freely within a bore drilled in theface of the material, such as coal, to be mined and broken down. One endof the tubular body is provided with a neck portion of slightly reduceddiameter which is screw threadedly attached to the head 2 as shown at 3.The seal between the tubular body and the head is completed by asuitably mounted annular resilient sealing means 4. A metallic sealingring 5 is positioned adjacent the end of the tubular body 1. As shown inthe drawing, the internal diameter of the metallic sealing ring 5 isslightly less than the internal diameter of the tubular body and themetallic sealing ring has its greatest effective cross sectional areafacing the end of the tubular body. A peripheral flange 6 extendsoutwardly from one end of the metallic sealing ring and cooperates withshoulder 7 on head 2 so as to limit the movement of the sealing ringaway from the terminal portion of the body. The sealing ring is slidablewithin the body and a sliding seal is maintained between these twomembers by means of an annular resilient sealing means such as O-ring 8in groove 9. That end of the metallic sealing ring remote from flange 6preferably terminates in a knife edge or an area of reduced diameter asshown at 10. This knife edge cooperates with the base of the sleevevalve 11 to form a metal-to-metal seal. Alternately, the end of thesealing ring can be fiat so as to provide a greater area for themetal-to-metal seal between the ring and the sleeve valve. The sleevevalve is slidable within head 2 and its movement therein is restrictedin one direction by metal sealing ring 5 and in the other direction bythe shear pin 12 as well as shoulder 28 on head 2 and the annular airpocket 13 formed by the juncture of the terminal portion of head 2 andend plate 14. The skirt 15 of valve 11 preferably terminates in anannular knife edge normally in contact with the shear pin 12. However,the cross sectional area of that portion of the skirt in contact withthe shear pin can be modified depending upon the desired firing pressureand the strength of the pin. Although the end of the skirt as shown isbeveled toward the interior, the terminal portion of the skirt canassume any desired configuration.

The shear pin 12 is normally held in position by reraining clip 17attached by suitable means to piston 18 both of which are urged towardthe shear pin by helical spring 19. Vent 20 in the base of sleeve valve11 provides a means of communication between main chamber 21 andsecondary chamber 22. The sealing of chamber 22 is completed by O-ring23 between the piston 18 and the skirt 15 of the sleeve valve. Theinternal portion of the end plate 14 is preferably provided with afacing or shear ring 24 which cooperates with the knife edge 16 on theskirt to sever the shear pin.

In operation, shear pin 12 is inserted through slot 25 and isresiliently held between retaining clip 17 and shear ring 24. Compressedgas is then introduced into main chamber 21 by conventional means notshown and gas passes through vent 20 into the secondary chamber 22.Consequently, the pressure in these two chambers is substantially equal.Thus, piston 18 is urged into close proximity with shear pin 12 by airpressure in coopera tion with spring 19. As the gas pressure increases,metal sealing ring 5 is urged into tighter contact with sleeve valve 11due to the diiferential effective areas of the metal sealing ring. Asthe pressure in the main chamber 21 increases to a point sufiicient toovercome the resistance of shear pin 12, the pin is cut by the knifeedge 16 permitting the valve 11 to slide toward end plate 14 and awayfrom discharge ports 26. The charge of compressed gas in main chamber 21is thus completely and instantaneously released to the surrounding workface which is to be broken down. The movement of valve 11 after ventingthe ports is restricted by cooperation of flange 27 on the base of valve11 and shoulder 28 in head 2 as well as by the cushioning effect ofannular air pocket 12. When the charge of gas leaves main chamber 21releasing the pressure therein, sleeve valve 11 is returned to itsoriginal position by helical spring 19. The portion of the shear pinremaining in slot 25 is removed and replaced by another shear member.The cartridge is then ready to be refired.

In the embodiment shown in FIGURE 2, a different type of shearablemember and shearing means are employed. The same reference numerals willbe used to identify those structural features common to bothembodiments. Main chamber 21 with metal sealing ring 5 and O-ring 8 andknife edge 10 to provide a metal-tometal seal is identical to thestructure described in connection with FIGURE 1. In this embodiment,however, the shear pin 12 is replaced with a rotatable shear plate 29.The piston 18 is urged into contact with the internal portion of shearplate 29 by helical spring 19 in the same manner as in the precedingembodiment. Stop pins 36 positioned in holes 38 in the skirt of sleevevalve 11 maintain the piston 18 in position. However, due to the planarconfiguration of the plate, retaining slip 17 can be eliminated. Theentire periphery of the skirt 15 of sleeve valve 11 does not contact theshearable member 29 but only a portion of the skirt extends in the formof a projection 30 into contact with the shear plate. The preferred formof the sleeve valve is shown in FIGURE 3. This projection is generallysmall in relation to the circumference of the skirt and preferablyrepresents an arc of about 10. The shear plate 29 is provided with anon-circular central perforation 31 as best illustrated in FIGURE 4. Endplug 32 is provided with an interior terminal portion 33 having a crosssectional configuration similar to that of central perforation 31 inshear plate 29. The shear plate is ounted on this terminal portion 33 ofthe plug 32 as shown. The opposite end of the end plug 32 is providedwith a key socket 34 or any other suitable wrench receiving means. Plug32 is freely rotatable and is held in place by end nut 35. Theperipheral portion of shear plate 29 is positioned away from the mainbody of plug 32 by shear ring 24.

The shell shown in FIGURE 2 operates much in the same manner as the onepreviously described. As gas under pressure is introduced into mainchamber 21, metallic sealing ring 5 is urged against the basal portionof sleeve valve 11 to form a metal-to-rnetal seal and the gas passingthrough vent into chamber 22 forces piston 18 into tight relationshipwith shear plate 29 and member 32. The movement of the valve 11 awayfrom ports 26 is retarded until the pressure built up in main chamber 21is sufficient to overcome the resistance of the shear plate 29. When theforce exerted by the gas in V the main chamber against sleeve valve 11exceeds the sum of the opposing force exerted on the sleeve valve by thegas in the secondary chamber 22 and the resistance offered by spring 19and shear plate 29, projection 30 suddenly passes through a portion ofthe shear plate and the valve slides away from and exposes ports 26.Here again, the movement of the sleeve valve after venting is restrictedby cooperation between flange 27 on the valve and shoulder 28 on thehead. After the cartridge has been fired, the sleeve valve isreturned toits original position by helical spring 19. Plug 32 is rotated throughan angle of about 22 by means of key socket 34, resulting incorresponding rotation of shear plate 29. V The projection 35.) on thesleeve valve is then opposed by another solid portion of the shear plateand the shell is in condition for refiring.

The projection 30 on the valve 11 normally has a thickness substantiallyequal to the thickness of the valve skirt 15 but can vary greatly inwidth. This projection can thus constitute from'3% to slightly less than50% of the periphery of the skirt 15. The number of shots that can befired with one shear plate increases as the width of the projectiondecreases. Thus, when the projection extends about half way around theskirt, only two shots can be fired with one shear plate. However, thenumber of shots can readily be increased to about 16 or 18 by reducingthe width of the projection to about a 10' are on the periphery of thesleeve valve skirt 15. Variations in the width of the projection alsoprovide a means of determining the pressure at which the gas in the mainchamber will be released. In addition, the firing pressure can becontrolled by the thickness and strength of the shear plate. While inthis embodiment, the projection penetrates the peripheral portion of theshear plate, it should be understood that such penetration can be madethrough more centralized locales in the shear plate.

After all portions of the shear plate have been used, it is readilyremoved by unscrewing end nut 35. Removal of this not frees rotatableplug 32 and the shear plate is easily removed through slot 37. Thecondition of the shear plate and the requirement for replacing it canreadily be observed through slot 37.

The shell of this embodiment can be readily provided with means torotate the shear plate each time the sleeve valve goes through itsfiring cycle. In this way, the shell can be fired automatically untilall usable portions of the shear plate have been expended.

While two specific embodiments of the present invention have been shown,various modifications will suggest themselves to those skilled in theart. Thus, various types of valves, springs and resilient sealingmembers can readily be employed in place of those specificallydisclosed. Although the present specification is directed to blastingdevices, it will be appreciated that the invention is applicable to anyother type of apparatus in which a sudden release of gas under pressureis required.

What is claimed is:

1. A blasting device comprising a substantially cylindrical body, apressure chamber within the body having a lateral outlet, means forintroducing gas under pressure at one end of said body, the opposite endof said body having an end wall provided with intersecting longitudinaland transverse passageways, a pressure responsive sleeve valve slidablein said chamber and normally positioned to span and seal said outlet,the valve having a smaller effective cross-sectional area on that sideof the valve facing said end Wall than on the other side of the Valve, askirt on the sleeve valve extending toward said end wall to a shearmember, the skirt forming a secondary Chamber, means of communicationbetween the pressure chamber and the secondary chamber, an imperforatepiston slidably sealed within the secondary chamber, and resilient meansnormally urging said piston into retaining position with the shearablemember.

2. A blasting device comprising a substantially cylindrical body havinga main chamber for containing a charge of compressed gas, a lateraloutlet for the gas, a pressure responsive sleeve valve slidable in saidmain chamber and normally positioned to span and seal said outlet, thesleeve valve having a skirt extending away from the main chamber andterminating in contact with a shearable member, a secondary chamberwithin the skirt of the sleeve valve, means of communication between themain chamber and the secondary chamber, the sleeve valve having a largereffective cross-sectional area in the main chamber than in the secondarychamber, imperforate retaining means for the shearable member slidablysealed within the secondary chamber, and resilient means normally urgingthe retaining means into operative contact with said shearable member.

3. A blasting device comprising a substantially cylindrical body havinga lateral outlet, the body adapted to contain a charge of compressed gasand to release the charge at a predetermined pressure, a pressureresponsive sleeve valve slidable in said body and normally positioned tospan and seal said outlet, a rotatable reusable shear member, animperforate shear retaining means slidably sealed in said valve, and aprojection on the sleeve valve normally in contact with a minor portionof said shear member.

4. A blasting device comprising a substantially cylindrical body havinga main chamber for containing a charge of compressed gas, a lateraloutlet in the body, a pressure responsive sleeve valve slidable withinsaid main chamber and normally positioned to span and seal said outlet,a skirt on thesleeve valve extending away from said main chamber andterminating in contact with a shearable member, a secondary chamberwithin the skirt of the sleeve valve, means of communication between themain chamber and the secondary chamber, the sleeve valve having agreater effective cross-sectional area within the main chamber than inthe secondary chamber, a slidable sealing ring about the internalperiphery of the main chamber and in sealing relationship with thesleeve valve, the sealing ring having differential effective surfaceareas normally urging it in the direction of the shearable member, animperforate piston slidably sealed with the secondary chamber forretaining the shearable member, and resilient means within the secondarychamber normally urging the piston toward said shearable member.

5. A blasting device comprising a substantially cylindrical body havinga main chamber for containing a charge of compressed gas, a lateraloutlet for the gas, a pressure responsive sleeve valve slidable withinsaid main chamber and normally positioned to span and seal said outlet,a skirt portion of the sleeve valve extending away from the mainchamber, a projecting segment of the skirt portion terminating incontact with a shearable member, a secondary chamber within the skirt ofthe sleeve valve, the sleeve valve havinga greater eflectivecross-sectional area in the main chamber than in the secondary chamber,means or" communication between the main chamber and the secondarychamber, an imperforate piston slidably sealed within the secondarychamber for retaining the shearable member in operative position, andresilient means within the secondary chamber normally urging the pistoninto contact with said shearable member and urging the sleeve valve to aposition spanning said outlet.

6. The blasting device of claim 5 in which the shearable member is arotatable disc.

7. A blasting device comprising a substantially cylindrical body havinga main chamber for containing a charge of compressed gas, a lateraloutlet for the gas, a pressure-responsive sleeve valve slidable in saidmain chamber and normally positioned to span and seal said outlet, thesleeve valve having a skirt extending away from the main chamber with atleast a portion of the skirt terminating in contact with a shearablemember, a secondary chamber within the skirt of the sleeve valve, meansof communication between the main chamber and the secondary chamber, thesleeve valve having a larger effective cross sectional area in the mainchamber than in the secondary chamber, an imperforate piston slidablysealed within the skirt of the valve, said piston retaining theshearable member in operative position in response to pressure withinthe secondary chamber, and resilient means normally urging the retainingmeans into contact with said shearable member, said shearable memberbeing adapted to be penetrated by at least a portion of the valve skirtacting in response to main chamber pressure.

References Cited in the file of this patent UNITED STATES PATENTS2,435,116 Armstrong Jan. 27, 1948 2,750,886 Filstrup June 19, 19562,794,395 Hesson et a1 June 4, 1957

